A groundbreaking phase II clinical trial has demonstrated that a simple modification to the 18F-flotufolastat PET/CT imaging protocol can significantly enhance the detection of prostate cancer recurrence in post-prostatectomy patients. The study findings reveal that concurrent administration of furosemide with the radiotracer substantially improves visualization of cancer lesions by reducing urinary bladder activity.
Enhanced Detection Through Innovative Protocol
The prospective trial (NCT05779943) enrolled 20 men with biochemical recurrence following prostatectomy, each presenting with prostate-specific antigen (PSA) levels of at least 0.1 ng/mL. The median PSA among participants was 0.61 ng/mL, with an interquartile range of 0.18–1.15 ng/mL.
The research protocol involved comparing two 18F-flotufolastat PET/CT scans per patient – one with 20 mg of intravenous furosemide administered alongside the radiotracer, and another without. This head-to-head comparison provided robust data on the protocol's effectiveness.
Significant Improvement in Imaging Metrics
The results showed remarkable improvements in imaging parameters with the diuretic protocol. Bladder activity measurements revealed:
- Median SUVmax decreased from 13.35 to 4.20 with furosemide (p = 0.014)
- Median SUVmean reduced from 10.00 to 2.95 with furosemide (p = 0.017)
Most notably, the detection rate of prostate bed recurrence increased significantly from 60% without furosemide to 85% with furosemide (p = 0.025). This 25% improvement in detection rate represents a clinically meaningful advance in diagnostic capability.
Clinical Implications and Safety
The study demonstrated that both furosemide administration and bladder distention independently contributed to reduced bladder activity. While bladder distention alone showed some benefit in reducing activity, the combination with furosemide proved most effective.
Importantly, the modified protocol eliminated the occurrence of peribladder halo artifacts, which were observed in three cases without furosemide use. This improvement in image quality further supports the protocol's clinical utility.
Technical Advantages of 18F-Flotufolastat
18F-flotufolastat, targeting prostate-specific membrane antigen (PSMA), already boasts the lowest urinary excretion among FDA-approved PSMA radiopharmaceuticals. This characteristic, combined with the new diuretic protocol, positions it as an increasingly valuable tool for detecting prostate cancer recurrence.
The enhanced protocol maintains equivalent detection rates at the per-patient, pelvic, and extrapelvic regions while significantly improving local recurrence detection. This advancement is particularly crucial for patients with early biochemical recurrence, where precise localization of disease can guide treatment decisions.
